4443 Exam 2 Study Guide Comfort fall 82 86 F Human Comfort Comfort is freedom from pain freedom from discomfort It is a neutral state Comfort is a pleasant state of physiological psychological and physical harmony between a human being and the environment Comfort is relative subjective psychological physiological thermal sensorial and mobile Psychological Comfort implies that individuals need specific garments fabrics colors and design features to help them feel confident and at ease within the context of the various roles they assume Roles Factors Self Image Relationship with others Trust love and respect Need of privacy Solitude silence anonymity Physiological Comfort refers to maintenance of thermal balance The proper relationship between body heat production and loss Factors Cardiovascular system Skeleton muscular system Central nervous system Pulmonary system Digestive system Physical Aspects of Comfort refers to different sensations and feelings of discomfort and or pain which influence the two types of comfort Thermoregulatory mechanism Factors Touch Sight Hearing Taste Smell Comfort Related Physical Properties of Textiles Thermo physiological Comfort Thermal resistance Water vapor permeability breathability Wick ability Water resistance repellency and proofness Drying rate Sorption of water Sensorial Neuro physiological Comfort Prickliness itchiness inflammation Roughness Thermal character warm cool feeling Electrostatic propensity Body Movement Comfort Stretch Weight Pressure compression Hand A tactile sensation may be by touch or sight We will be using touch Usually a subjective assessment Affected by Body temperature Room temperature Psychological state of being Physiological state of being Association Subjective Hand You will be touching the fabric with you eyes closed Pliable to stiff Stretchy to non stretchy Springy to limp Smooth to rough Compact to open Cool to warm Will rate the fabric on a scale from 1 7 on the following Harsh to slippery Fabric Drape Soft to hard The manner in which a fabric hangs falls over a 3 dimensional form How a fabric bends under its own weight is an indication of drapability Drape occurs when only part of the fabric is directly supported and gravity produces deformation in the unsupported portion Fabrics that fall in numerous vertical folds are highly draped able There is not a standard requirement you have to make a judgment call The range is 0 100 called the drape coefficient Generally above 50 is considered stiff and not very drapable Some fabrics are considered not drapable most denim for jeans for example What affects drapability 1 Fiber content Some fibers are more stiff than others depends on size and inherent characteristics Rayon is known for drapability 2 Yarn structure Tightly constructed yarns will have less drapability 3 Fabric structure High fabric count makes a compact structure which will likely have less Loosely constructed yarns will have more drape Combination of fabric structure and yarn structure Moisture Absorbency Ability of material absorbent to take in or absorb another material absorbate Ability to retain liquid water in interstices pores and internal portions Evaluate how quickly liquid absorbed and quantity absorbed at saturation point Testing Water repellency relative resistance of material to surface wetting water penetration or water absorption Water resistance ability of material to withstand penetration by water under pressure or water that drops from distance and strikes against material with known force Waterproof materials resistant to water penetration regardless of pressure or force AATCC 22 Water Repellency specimen placed on spray tester distilled water poured through spray nozzle and pattern produced by surface wetting evaluated using spray test rating scale AATCC 35 Water Resistance Rain Test assess suitability of materials for umbrellas rainwear and hats weighed before testing sprayed with water using rain tester weight gained calculated Water Vapor Transmission Dessicant method known weight of dried calcium chloride placed in container Speed with which water vapor passes through material covered by material weight gain Water method specimen covers pan containing known amount of water water loss by evaporation measured Both procedures measure water transmitted in 24 hour period Physical Characteristics of Textile Materials Influencing Thermal Comfort Fabric Mass Fabric Thickness Fiber Yarn and Fabric Structures Porosity is the ratio of air space to the total volume of the fabric expressed as a percentage Cover Factor is defined as the opacity or hiding power in textiles Body metabolism The Physics of Human Comfort Heat transfer Evaporation Heat Transfer refers to the transfer of heat energy from one environment to another Heat Transfer Heat transfer occurs whenever a temperature difference DT exists between two environments heat moves from the warmer surface or area to the cooler surface or area The rate at which heat is transferred depends on DT as well as any resistance imposed between the two environments Modes of Heat Transfer Conduction is the transfer of heat by physical contact either within a body or between two touching bodies Convection is heat transfer via a moving air mass within space Radiation involves heat transfer through space in the form of electromagnetic energy Effect of Fabric Properties on Heat Transfer Fiber type and structure Yarn type and structure Fabric type and structure Finishes applied Electrostatic Propensity Anti static finishes Measure of capacity of noncuducting material to acquire and hold electrical charge Electrostatic cling propensity of one material to adhere to another because of surface electrical charges Time required for charge to decay so that electrical attractive forces causing specimen to cling to metal surface are overcome by gravitational forces pulling specimen away Conditions for static electric charge buil up are cool dry environment Manufactured fivers build up static electric charges because they are hydrophobic and do not allow conduction of electrical charges Healthy adult human body can tolerate about 5000 volts 5kV of electrical charges In some areas that is too much for safety In sensitive areas where there might be life sustaining equipment or other electronics the maximum allowable is 3500 v 3 5kV In areas where there would life threatening situations the maximum allowable is 2500 v Anti static finishes work by making the material a